We reported last week that Google announced it will introduce an official in-app billing platform for its Android operating system. It was made available for testing last week, but the system officially went live today. Developers are now able to publish apps with in-app payments, allowing users to make purchases within those apps.

Google’s Eric Chu said In-app Billing gives developers more ways to monetize their apps with try-and-buy, virtual goods, upgrades, and other billing models.

As we mentioned, Disney-owned Tapulous was rearing to get into the Android Market once the in-app payment system was launched on the platform. Lo and behold, several apps are launching today that are using the service, one of which is Tapulous’ Tap Tap Revenge. The other apps using the service are Comics by ComiXology; Gun Bros, Deer Hunter Challenge HD, and WSOP3 by Glu Mobile; and Dungeon Defenders: FW Deluxe by Trendy Entertainment.

According to PCMag, Chiu said back in January that he was “definitely not happy” with the Android Market’s lack of in-app purchases. He told developers that merchandising, payments, discovery, and downloading were top priorities for them.

The inclusion of In-App Billing is great news for developers, since before today, the only way to make a profit was by selling the app itself. Now developers can offer the app for free or at a discounted rate if the goods offered within the app will get users to start spending money.

Chu said that to try In-app Billing in your apps, developers can start with a detailed documentation provided on the Android Developers blog, and complete a sample app provided, which shows how to implement the service in your app, set up in-app product lists, and test your implementation. He stresses that it’s “absolutely essential” that developers review the security guidelines to make sure the billing implementation is secure.